Briefly describe what's a virtual DOM

• Java: • How HashMap works internally • Exception handling: types of exceptions and how to handle them • Garbage collection in Java • Java 8 features (e.g., Streams, Lambdas, Optional, etc.) • Spring Framework: • Inversion of Control (IoC) and Dependency Injection (DI) • Throwing exceptions in Spring (e.g., using @ExceptionHandler, @ControllerAdvice) • Spring JPA and its methods (e.g., save(), findById(), delete()) • SQL: • Difference between DELETE and TRUNCATE • Five categories of SQL (e.g., DDL, DML, DQL, DCL, and TCL) • AWS: • Basic understanding of AWS services and their applications.